Substrate-level phosphorylation | Biochemistry

Quick Orientation

Section	Objective	Keywords
Definition	Understand the core idea	Substrate-level phosphorylation
Reaction in the Citric Acid Cycle	Follow the sequence and key control points	GTP + ADP ↔ ATP + GDP
Requirement of O2 by TCA Cycle	Follow the sequence and key control points	O2, aerobic, NAD+
Energetics of the Citric Acid Cycle	Follow the sequence and key control points	4 reducing equivalents, NADH, FADH2
Clinical Correlation	Connect the mechanism to clinical findings	Clinical Correlation

Section

Definition

Objective: Understand the core idea
Keywords: Substrate-level phosphorylation

Reaction in the Citric Acid Cycle

Objective: Follow the sequence and key control points
Keywords: GTP + ADP ↔ ATP + GDP

Requirement of O2 by TCA Cycle

Objective: Follow the sequence and key control points
Keywords: O2, aerobic, NAD+

Energetics of the Citric Acid Cycle

Objective: Follow the sequence and key control points
Keywords: 4 reducing equivalents, NADH, FADH2

Clinical Correlation

Objective: Connect the mechanism to clinical findings
Keywords: Clinical Correlation

Definition

Substrate-level phosphorylation: in the citric acid cycle, GDP + Pi → GTP directly, one such event per turn of the cycle (distinct from oxidative phosphorylation of NADH and FADH2 via the electron transport chain).